The goal of this competing continuation project is to test models of the development and prevention of three inter-related antisocial problems in young adulthood: violence, substance abuse, and risky sexual behavior. Joint consideration of these three diverse problem domains holds promise because of the syndemic of parallel epidemics, comorbidity, similar epidemiology, and the possibility that isolated prevention efforts fail precisely because of the failure to consider joint effects. The investigators will test three major hypotheses: 1) these problems are comorbid across development, with early conduct problems leading to each adult outcome; 2) a comorbid antisocial behavior pattern develops as a dynamic cascade, in which early risk factors dispose a child to later risk factors, which lead to problem outcomes. The model posits gene-environment interactions that are mediated through acquired social information-processing patterns. Domain-specific outcomes also develop through specific affordance experiences; and 3) random assignment to preventive intervention will reduce the probability of each of antisocial outcome in adulthood, with moderation by genetic and early-life factors and mediation by intervention effects on early conduct problems and social-cognitive patterns. The samples come from two independent, ongoing prospective studies of conduct disorder, the Child Development Project (CDP) and Fast Track (FT). The CDP has followed a community sample of 585 preschool males and females who are now 26 years old, with high (90 percent) retention after 22 years. The FT Project is a multi-site randomized clinical trial, in which 891 early-starting, conduct-problem youth (31 percent girls; 51 percent African-American) were assigned in kindergarten to receive (or not) a 10-year comprehensive intervention to prevent conduct disorder and have been followed through age 24 with high (83 percent) retention of participants. In the proposed project, identical measures of violence, substance-use problems, and risky sexual behaviors will be assessed in the CDP through age 31 and in FT through age 29. Growth analyses, confirmatory factor analyses, and structural equation modeling will test hypotheses. Relevance to public health: This project will contribute to the discovery of ways to prevent young adult antisocial problems, including violence, substance abuse, and risky sexual behaviors.